Thread-cutting mechanism for sewing-machines



W. L. BARRON AND F. E. OSOLI THREAD CUTTING MECHANISM FOR SEWINGMACHINES.

APPLICATION FlL ED Aus.3.191e.

1,836,808. Patented A r. 13, 1920.

' 2 SHEETS-SHEET l.

6 5 v j w Q T M A I 35 5. 1 6

W. 'L. BARRON AND F. E. OSOL.

, THREAD cunma MECHANISM FOR SEWING MACHINES.

APPLICATION FILED AUG-3| I9I6. 4 1,336,808, Patented Apr. 13, 1920.

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A TTORNEY WILLIAM I1. BARRON, OF NEW YORK, N. Y.,

AND FRITZ E. OSOL, 0F ELIZABETH, NEW

JERSEY, ASSIGNORS TO THE SINGERqMANUFAG'J-URING COMPANY, A. CORPORATIONOF NEW JERSEY.

THREAD-CUTTING inner-murmur non SEWING-MACHINES.

" Application filed August 3.

To all whom it may concern:

Be it knownthat W6,'WILLIAM L. BARRON and FRITZ E. OsoL, citizens of theUnited States, residing, respectively, at New York, in the county of NewYork and State of New York, and Elizabeth, inthe county of Union andState of New Jersey, have invented certain new and useful Improvementsin Thread-Cutting Mechanisms for Sewing-Machines, of which the followingis a specification, reference being had therein to theaccompanying'drawings.

This invention relates to improvements in thread pull-off. and cuttingmechanisms for sewing machines and especially for that class of sewingmachines in which the mechanism is automatically stopped afterproduction of a predetermined H number of stitches, as for example inbutton sewing machines.

The objects of the present invention are to providemeans to lift thework-gripping elements and to pull 01f a sufficient quantity of theupper and lower threads of a two-thread sewing machine for the beginningof a succeeding sewing'operation and to sever said threads.

In its preferred embodiment this im provement has been applied to abutton sewing machine employing separate buttonholder and Presser-footbars having common lifting means, and comprises a needlethreadpull-oflarm, fulcrumed on a bracket sustained by the frame of the machine andactuated by the lifting of'the button-holder resser-bar, and aneedle-thread severing device supporteduby the presser-foot bar andactuated by themovement of the pull o'fi arm. A shuttle-thread pull-offand severing device is provided comprising a bar reciprocable in asuitable guideway of the .worksupport and actuated by connection withthe button-holder and presser-foot lifting means. The forward end of thebar is provided with a thread pull-01f portion and backward thereofwitha thread-severing knife to-first pull off a suflicient quantity ofshuttle-thread and then sever the same.

1 In the accompanying drawings, Figure 1 is a rear side elevation andFig. 2 a front end elevation of a button sewing machine embodying thepresent invention. Fig. 3 is a rear view of the presser-foot supportingSpecification of Letters Pat ent. Patented Apr. 13,

1916. SerialNo. 112.907.

bracket with "the lower-thread cutter sustaining bracket shown insection. Figs. 4 and 5' are detail perspective views of the componentparts of the lower-thread cutter guiding and sustaining bracket. Fig. 6is a detail perspective view of the lower-thread cutter andpull-off bar.Fig. 7 is a detail perspective view of the resser-foot and itssupporting bar. Fig. 8 is a detail perspective view of the; presser-footbar guiding bracket. Fig. .9 is a detail perspective view of thepresser-foot bar. lifting spring and its supporting collar. Figs 10 and11 are detail perspective views respectively of the needle-threadpull-off arm and of the needlethread cutter.

The machine, as shown, is constructed with a frame comprising a hollowstandard 1 with the lateral work-sustaining arm or horn'2 and the hollowoverhanging arm 3 in which latter is journaled the main-shaft a carryingat its rearward end the fast and loose pulleys 5 and 6 and at theforward end the take up cam cylinder 7. This cam-cylinder is providedwith a crank-pin 8 connected by means of the pitman 9 with the usualstud upon the collar 10 fixed upon the needle-bar 11 which carries theeye-pointed needle 12. The reciprocating needle-bar 11 is journaled inthe swinging frame 13, fulcrumed within the head of the bracket-arm andprovided with a lateral arm 14 operatively connected by means of a link15 with a lateral arm 16 carried'by one end of a rock-shaft 17. Therock-shaft 17 at its opposite end carries an arm18 having a roller-stud19 entering a cam-groove formed. in a cam-wheel 20. The cam-wheel 20 iscarried by a transverse shaft 21 suitably rotated from the mainshaft 4by means of a worm-wheel 22 and worm 23.

The shaft 21 also carries a stop-motion controlling cam 24?, shownpartly in full and partly in'dotted 'lines. The surface of the-controlling caml2 l contacts with a rollerstud 25 carried by abellcrankdever 26, fulcrumed at 27 upon the frame 1 of the machine andsuitably connected with an ordinary form of stop-motion device.

Cooperating with the needle 12 is the oscillating shuttle 28 journaledin the race 29 and provided with the thread-case 30. The

shuttle is actuated by means of the driver 31 at the forward end of therockshaft 32 mounted within the horn 2 and having at its rearward endthe crank 33 actuated in a well-known manner by means of the pitman 34connected with the crank 35 of the main shaft 4.

The button-holder supporting presser-bar 36 is journaled in the head ofthe bracket arm and has adjustably secured thereto by means of theset-screw 37 the collar 38, having a forked arm 39 embracing theguiderod 40 and the upwardly projecting arm 41 having a lateral lug 42adapted for engagement by the forward arm 43 of a lifting lever mountedupon the fulcrum screw-stud 44 sustained by the frame of the machine.The lifting lever has a rearwardly extending arm 45 and pivoted theretoby means of the screw 46 is a link 47 to which is at tached a rod 48having suitable connection with a treadle. Surrounding the presserbar 36is a spring 49 interposed between the collar 38 and the upper bearing ofthe bar. The resser-bar 36 sustains the buttonholder 50 more fullydisclosed in another application filed simultaneously herewith.

The presser-foot supporting presser-bar 51 is mounted for verticalreciprocation in a guideway 52 formed in a bracket 53 secured by meansof screws 54 and 55 to the frame of the machine and is slidinglymaintained in the guideway by screws 56 and 57 the shank of the screw 56passing through an elongated slot 58 formed in the presserbar andentering a threaded aperture 59 formed in the bracket 53, and the screw57 passing through an elongated slot 60 formed in the bracket andentering a threaded aperture in the rear side of the presser-bar 51. Thepresser-bar 51 has secured thereto by means of screws 61 and 62 theshank 63 of the presser-foot 64 serving to hold the work in positionduring the sewing operation and formed with a guideway 65 for theneedlethread severing knife-blade 66.

The knife-blade 66 is provided with a cutting edge 67 andis maintainedin the guideway 65 by means of a retaining plate 68 secured. by screws69 and 70 to the presser-foot and provided with a stationary cuttingedge 71 against which the movable knife-edge 67 acts to sever the needlethread extending upwardly from the work to the eye of the needle throughthe cut-out needleslot 72 formed in the presser-foot. The

' knife-blade 66 is formed with an upstanding ear 73 having loosepivotal connection with a depending arm 74 of a sleeve 75 j ournaled onthe fulcrum screw-stud 7 6 threaded into an aperture 77 in thepresser-bar 51.

The sleeve 75 has a lateral projection 78 adapted for engagement by astud 7 9 pro jecting laterally from the plate 80 pivotally attached bymeans of the screw 81 to a bracket 82 secured, as by screws 83 andv 84,

to the frame of the machine. Adj ustably secured to the plate 80 bymeans of the screw 85 is the needle-thread pull-off arm 86 provided withthe thread-engaging nose 87 adapted to be swung across the needle-pathand to engage the needle-thread when the button-holder is lifted atthe-completion of a sewing operation and to pull off a sufficientquantity of thread through the eye of the needle to restart the sewingoperation. To impart the vibratory pull-off movements to the arm 86 theplate 80 is provided with an elongated slot 88 entered by a pin 89projecting from the collar 90 secured to the button-holder presser-bar36. Consequently, as theplate 80 swings on its pivot, the pin 79 engagesthe projection 78, thereby rocking the sleeve 75 on its fulcrum-stud andactuating the knife-blade 66 to sever the needle-thread close to andabove the work, sufficient clearance being provided between the pin 79and the projection 7 8 to properly time the thread-severing actionsubsequently to the pull-01f action. A spring 91 secured to a laterallyprojecting stud 92 on the presser-foot bar 51 engages the depending arm74 and serves to retract the knife-blade 66 after its cutting action, astop-screw 93 carried by the knife-blade limiting its retractingmovement by engagement with a shoulder formed by a notch 94 in thepresser-foot.

The presser-foot 64 is normally held yieldingly against the work underthe action of the spring 95 of which one end is secured to thepresser-foot bar bracket 53 by means of the screw 96 and of which theother end bears downwardly upon the stud 92. In order to lift thepresser-foot when the button-holder is lifted, the collar 90 is providedwith a projecting arm 97 to which is secured by means of the screw 98one end of the bent plate-spring 99 of which the other end is adapted toengage the under side of the stud 92 carried by the presser-bar 51. Theactuation of the lifting lever43, 45 therefore causes the lifting of thebutton-holder and of the presser-foot and causes the needlethread to besuccessively pulled of and severed.

Secured to the forward end of the laterally projecting horn '2 by screwspassing through apertures 100 and 101 is a curved bracket-plate 102having a flattened portion 103 provided with a raised work-supportingseat 104 formed with a needle-slot 105. Secured to the portion 103 ofthe bracket 102 is one end of a guide-bar 106 attached at its other endto the horn 2 by means of the screw 107. This guide-bar is formed with aslideway 108 that supports and guides the lower-thread pull-off andsevering bar 109 formed at its forward end with a pull-ofi edge 110 andcarrying backwardly thereof the thread-cutting blade 111 having aknifeedge 112. The rearward end of the bar 109 is provided with an ear113 pivotally connected by means of thescrew 114 with one end of thelink 115 of which the other end is pivotally connected to an arm 116 ofa bellcrank-lever fulcrumed at 117 to the frame of the machineand havingits other arm connected to the link 47 provided with thetreadle-actuated'rod 418.

At the completion of a sewingoperation, the operator depresses thetreadle-actuated rod l8 and thereby rocks the bellcrank-lever work andpull 1 against the inner edge ofthe tongue 118 which is secured 116 onits fulcrum and actuates the bar 109, so that its forward end 110 threadextending from the loop-taker to the off a quantity of thread to theunder side of the bracket-plate 102 so as toenter the space between theknife-blade 111 and the pulloff portion 110 of the bar 109, asillustrated in 'Fig. 3 of the drawings. In the continued forwardmovement of the bar 109, theknifeedge 112 engagesthe taut thread andsevers the same. The depression of the rod 48 also rocks the lifter-arm45 on. its fulcrum 4:1 and lifts the button-holder 50 and thepresserfoot 6 1 through the connections previously described, therebyactuating the arm 86 to pull off the needle-thread and the blade 66. tosever the same against the stationary.

knife-edge 71..

The present improvement therefore provides simple upper and lower threadpulloff and severing. elements actuated by a single treadle-connectionthat is adapted also tolift the button-holder and presser-foot forreleasing the work, When the-treadle is released the several parts arerestored to will engage the presser-foot, and upper and lower threadpull-off and severing devices, of buttonholder lifting means andconnections therewith for lifting the presser'foot and actuating thepull-off and severing devices.

2. In a button sewing machine, the combination with stitch-formingmechanism including a needle, a button-holder, a workholdingpresser-foot, a needle-thread pulloffdevice and a needle-thread severingdevice, of means for lifting said button-holder and means brought intoaction by the lifting of said button-holder for lifting the presserfootand for needle-thread. I

3. In a two-thread button sewing machine, the combination with abutton-holder,

a work-holding presser-foot movable relatively to said button-holder, Iand lowerthread pull-01f and severingelements, of means for lifting saidbutton-holder and connections therewith for lifting said presser-footand for actuating said lowerthread pull-off and severing elements.

In testimony whereof, we have signed our names to this specification.

WILLIAM L. BARRON. FRITZ E. osoL.

pulling off and severing said

